Abstract
In plant meristems, dividing cells interpret positional information and translate it into patterned cell differentiation. Here we report the molecular identification of the
Arabidopsis HOBBIT
gene that is required for cell division and cell differentiation in meristems. We show that it encodes a homolog of the CDC27 subunit of the anaphase-promoting complex (APC). HOBBIT partially complements a yeast
nuc2/cdc27
mutant. Unlike other CDC27 homologs in
Arabidopsis
, its transcription is cell cycle regulated. Furthermore,
hobbit
mutants show a reduction in
DR5 :: GUS
auxin reporter gene expression and accumulate the AXR3/IAA17 repressor of auxin responses. HOBBIT activity may thus couple cell division to cell differentiation by regulating cell cycle progression in the meristem or by restricting the response to differentiation cues, such as auxin, to dividing cells.